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    <title>Document</title>
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<script>
// JS中通常使用的小括号：()

// 1.小括号用于调用执行函数
// function fn(){
//     console.log( 1234 )
// }
// fn();

// 2.小括号用于 '分组'
console.log( (2+3)*4 );// 分组的作用是提高运算优先级

var a = 123;
var b = 456;
var c = 789;
console.log( a,b,c );// 123 456 789
console.log( (a,b,c) );// 789
console.log( a.toString() );// '123'
console.log( (123).toString() );// '123'

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